Posts Tagged ‘BKL’
by B.B. Pelletier
Well, here is our old friend, the San Anselmo Beeman 124, again. Today, I’ll address the scope problems I was having the last time I tested the rifle for accuracy.
You may recall that I suggested that the front and rear rings be swapped to see if that would alter the amount of down angle the rifle appears to have. One reader was appalled that anything manufactured could be that far off from true, but believe me, it doesn’t take much. I’ve seen this trick work many times in the past. However, I failed to mention that three inches is a bit excessive to try to correct this way. This trick is more for those who optically center their scope and have a half-inch problem at the first point of intersection.
However, I did remove the rings and swap the front for the rear. Because these are two-piece rings I could also turn one ring at a time, giving me six different permutations of the setup, I believe. But three inches of change is so major that if it doesn’t come by swapping positions, you might as well look elsewhere.
Well, I was right. Swapping the rings did make a big difference. Only the difference went the wrong way. Now the pellet was striking the target four inches below the aim point, using the exact same scope with no adjustments. So, this set of rings was history. No amount of shimming would ever be able to make up an angular difference that large.
However, I had an ace up my sleeve. I’d visited the AirForce factory and asked to borrow a BKL drooper scope mount, and they happily complied. So, now I had the BKL 260 with .007 drop compensation to try out. This is a one-piece mount and it comes with simple instructions for which way to mount it. However, I did encounter a problem. This BKL mount is too low to allow the 50mm scope I had been using to clear the 124 spring tube. And you’ll recall that I have to use a BKL mount because of the 124′s non-standard scope stop system. I have mounts that will work with it, but you can’t buy them, so I’m not testing them here.
The solution was to use another scope, and all I was trying to do was ascertain that there was a scope mount and ring set in the world for this rifle — a vintage 124 with a large barrel droop. So, I picked a BSA 3-9×32 scope that didn’t have parallax adjustment. As a result, I had to run it at five power or the target was too blurry to see well.
Even with all that disadvantage against me, I proved the concept. The 124 and this new scope adjusted on target perfectly with no problem of adjusting the elevation knob too high.
So, I shot one group of 10 Crosman Premier 7.9-grain pellets and then another. Sure enough, the problem has been solved.
I’m removing the scope from the gun, because the only reason I scoped it in the first place was to conduct the Silver Jets accuracy test. That’s over now, so the 124 can go back into its sarcophagus, except for one more tuneup that will employ the newest Pyramyd Air 124 piston seal.
by B.B. Pelletier
Getting ready to test
Today, I want to mount a scope on the 124 to get ready for the long-range accuracy test. Normally, I would just mount the scope and gloss over it in the report, because scope mounting is usually not a big deal; but the 124 is a special airgun that needs special scope mounting considerations. So, I’m making a separate report about it.
A strange scope stop
What makes the 124 special is the way Feinwerkbau went about providing a scope stop. You must understand that Feinwerkbau is a target gun company. They understand rear aperture sights very well, but they don’t appreciate scope sights nearly as well. And, in the 1970s — when the 124 came out — scope mounting was still very new to the hobby. They provided a scope stop system that works well for rear aperture sights but not so easy when working with scopes.
Their system consists of half-round grooves cut across the 11mm dovetail scope rails. The plan is for a round steel pin in the base of the rear scope mount or in the rear of the one-piece scope mount, if that’s what you use, to fit into one of those grooves. Once it’s in, the scope mount will stay put under recoil. It’s a simple system, but not one that’s widely used. Webley used it on the Patriot, and CZ used it on some of their rifles. Most airgun manufacturers use something else.
Pick one of those four grooves to accept a steel crosspin from the base of one of your scope rings or the rear of your one-piece scope ring. Once the base is tightened on the dovetails, the groove and pin prevent the base from moving under recoil.
Because of the low usage of this kind of scope stop system, there aren’t a lot of scope mounts with the necessary crosspin. Beeman sold them while the 124 was selling well, but they stopped offering them in the late 1990s. B-Square also made some just for 124s, plus they made a mount with two crosspins that was to be used on a Webley Patriot. You could always grind off or remove one of those two pins to make their mounts fit the 124.
This old B-Square one-piece scope mount has two crosspins to interface with the grooves on a Webley Patriot rifle. By removing one of the crosspins, this mount can be fitted to a 124.
Forget trying to just tighten the base screws to hold the mounts in place by friction. The 124 is a long-stroke spring-piston rifle that will walk any standard mounts — aluminum or steel — that you try to do this with. And, you can forget something else, too.
Some guys get the bright idea of taking a standard vertical scope stop pin and rounding it to a crosspin profile. Forget it. It doesn’t work. All it does is rip a wide groove straight back through the top of the steel receiver tube as the mount slowly walks backward under recoil. It may take six months of steady shooting before you notice it, but you’ll ruin your gun this way. There’s just not enough bearing surface on a single, thin vertical stop pin that’s been profiled in this way.
I have been testing airguns for a very long time now, and I have a drawer filled with exotic scope mounts, including some prototype units that never made it to market. There aren’t many airguns that I can’t scope, but my situation is not the norm. Most guys have to find a mount that works from what’s available today, and that can be daunting when the gun is an old-timer like the FWB 124.
Bring on the BKLs!
There may be a bright light on the horizon, though. Back when I was messing with 124 rifles, BKL mounts didn’t exist, but they do today and we’ve tested them on other spring rifles that recoil a lot harder than the 124. For those who aren’t aware, BKL mounts are the one mount on the market that can hold tight by just clamping pressure, alone. And, here’s the best part — they’re made from aluminum! So, as tight as you can make them, they’ll never damage the sharp edges of your rifle’s dovetails the way they would if they were made of steel.
For this test, I’ve installed a set of BKL-363H-MB scope mounts with double straps. Man, I wish these things had been around in the late 1970s!
I also found out something extra-cool about these double-strap BKL mounts. There’s no special torque pattern to be followed! Instead of tightening the scope caps by a prescribed pattern like you would the main bearings on a crankshaft to get the force evenly distributed over all four screws, these caps go down in a straightforward way. Tighten one side and the other. As simple as that. Because each strap has only two screws, there’s no way to screw up — pun intended!
I’ll watch the mounts to make certain they don’t move, but the groups I get should pretty well tell the whole tale without the need for any special testing. If I shoot tight groups, there can’t be any scope movement.
I chose a Leapers 3-9x50AO scope with illuminated reticle. I didn’t need the illuminated reticle, but this particular scope comes with a fine crosshair that will aid in getting a refined aimpoint. As long as the light’s good, I should be able to get great results with it.
So, that’s the saga of mounting a scope on a 124. It’s not any harder than installing a scope on any other spring rifle, but the mount situation is different enough to cause concern. Remember this — the FWB 124 was the very first air rifle to get a reputation for scopes slipping and even breaking. Though we have much more powerful rifles today, don’t underestimate the 124.
by B.B. Pelletier
This test has taken an inordinate amount of time, primarily because of my illness and some other pressing matters. We’re testing the BKL 260 mount to determine if its clamping pressure is good enough to prevent movement under recoil without a positive recoil stop.
In the last report, I tested the mount on a Hammerli Razor, a standard sporter spring rifle, and it held up fine. Over 500 shots later, it didn’t move. I’d planned to do a similar test on a Webley Patriot, which is the same as a Beeman Kodiak, but as the test drew near I decided that 500 shots were unnecessary — 100 shots would be sufficient. The Patriot/Kodiak is a spring-powered jackhammer that will move or break a scope in very few shots. Today’s test will demonstrate that. Mac switched the scope from the Hammerli Razor to the Webley Patriot generously provided by AirForce Airguns owner John McCaslin. Though this is a .177 caliber rifle, it still has all of the heavy recoil characteristics of the type.
The rails were first scrupulously cleaned with a swab and denatured alcohol. This step is essential to success with these mounts. Tape was placed behind the rear clamp and in front of the front clamp to monitor any mount movement on the rails. The same Bushnell Trophy 6-18×40 was used in this test to keep everything equal. Mac also put tape behind the rear ring and in front of the front ring to measure any movement of the scope in the rings.
Mac proceeded to the range to start shooting. After 8 shots, there was considerable scope movement in the rings.
Normally, the test would have ended right there, but Mac was given a small packet of a proprietary product that’s being developed by AirForce. The purpose of this product is to prevent mount movement in the dovetails of a gun. But, Mac figured it would also work on the rings and the scope tube. So he removed the ring caps, reset the scope to zero, and applied this product to the ring caps. Over the next 92 shots, there was no measurable movement in the rings.
The recoil of the Webley also loosened the front objective ring of the scope and separated it from the scope. Many old timers know that the Webley Patriot/Beeman Kodiak is the hardest spring rifle as far as recoil is concerned. Newer shooters are not aware of this, which is why I’m taking the time to explain all the damage this gun did.
So what’s the bottom line with this test? Did we succeed or fail? From the standpoint of the BKL mount not moving on the dovetail, the mount passed the test. However, with the movement of the scope in the rings, the test was not a complete success. The introduction of the proprietary non-slip product that AirForce is developing seems to have solved that problem, so BKL users should be able to use their mounts for almost any heavy recoil situation.